We design a waveguide crossing with composite subwavelength (SW) structures, i.e., bridged SW grating (BSWG) waveguide structures and diagonally periodic holes (DPHs), on a partial parabolic single layer crossing (PPSLC) to improve its transmission. The BSWG is located before/after the input/output regions of the PPSLC and the DPHs are in the crossing region of the PPSLC. This waveguide crossing occupies a footprint of 6.2 μm × 6.2 μm upon a silicon-on-insulator wafer with 220-nm silicon device layer on 2-μm buried oxide. We successfully gain simulated results of the transmission up to 98.72% (−0.056 dB) and the crosstalk as low as −65 dB at an input wavelength of 1.55 μm.
We demonstrate a record gain of 11.4-dB for 300-nm broadband single-mode Cr-doped crystalline core fibers (SMCDCCFs) employing a novel growth of smaller core. The gain-per-unit-length efficiency of the SMCDCCF is 38-dB/m, which is much higher than current Er and Bi-doped fibers of 0.3 dB/m. The record gain achieved is mainly due to constantly maintain conical molten-zone shape in growth process to fabricate a smaller core of 15-µm and a longer fiber length of 30-cm.
In this study, we propose and demonstrate a reflex optical phased array (OPA) chip, represents the most advanced optical scanning component of the third-generation LiDAR, and it has competitive advantages. The result showed the two-dimensional control of free-space optical fields at a wavelength of 1,550 nm at a 100 kHz modulation speed, which used dielectric thin film of SiN with an electro-optic response, realizing programmable space-variant control of optical wavefronts in a 32 × 4 pixel array at high speed. The 2D beam steering around a 30° × 2.5° field of view with the beam widths of 1.0° × 0.6°. We will provide custom solid-state LiDARs to clients, and these LiDARs will be more cost-effective than the commercial LiDAR products and will become more receptive by the autonomous vehicle market.
A low-cost transistor outline-CAN (TO-CAN) package, which is combined with flexible printed circuit board (PCB) and hard PCB, has been developed for a 25-Gb/s optical subassembly module. On the flexible PCB, the transmission line structure used top ground microstrip line, and the wider transmission bandwidth can be obtained. Using ground pads and ground notch technologies, the impedance of connection between flexible PCB and hard PCB was designed to match with the impedances of signal traces of the flexible and hard PCBs. In the TO-CAN package, a TO-46 header was used, and the header needs to closely connect with the flexible PCB. The bandwidth of TO-46 package combined with flexible and hard PCBs can achieve above 23 GHz. The clear 25-Gb/s transmission eye diagram was also measured, and the rise time, fall time, and Q-factor of the eye diagram are 13.78, 13.56 ps, and 8.76, respectively. The TO-46 package combined with flexible and hard PCBs has been verified to be suitable for application in 25-Gb/s optical subassembly modules.
A new 5-pin transistor outline (TO-Can) header for conventional coaxial laser package has been proposed and
demonstrated by using a three-dimensional full-wave electromagnetic simulation tool. The applicability of the simulation
tool was verified by a measurement result of a conventional TO-56 header. By adopting a two-session feed-through via
and a bent feed-lead, this TO-Can header has the optimal impedance for high-speed modulation. The reflection loss can
be controlled beneath -10-dB before 15-GHz with a 50-Ω termination. The 3-dB modulated bandwidth with a load
impedance of 5-Ω and 50-Ω is over 23-GHz and 37-GHz, respectively. This TO-Can header provides a low-cost coaxial
laser package solution with widely load impedances from 5-Ω to 50-Ω and may apply in the emerging 100-Gigabits
Ethernet (100GbE) and next generation Fiber Channel (20GFC) applications.
In this paper, we proposed the design of directional coupler integrated with ring resonator based on two-dimensional
photonic crystals (2D PCs) to develop a triplexer filter. It can be widely used as the fiber access network element for
multiplexer-demultiplexer wavelength selective in fiber-to-the-home (FTTH) communication systems. The directional
coupler is chosen to separate the wavelengths of 1490nm and 1310nm. The ring resonator separates the wavelength of
1550nm. The transmission efficiency is larger than 90%. Besides, the total size of propose triplexer is only 19μm×12μm.
We present simulation results using the finite-difference time-domain (FDTD) method for the proposed structure.
A 10 Gb/s bi-directional optical subassembly (BOSA) with an uncooled 1300nm DFB laser and a receiving PIN-TIA had
been assembled and characterized. This 10 Gb/s BOSA integrated a 45o-tilted thin film WDM filter which can transmit
the 1300nm light into the fiber and reflect the 1550nm light into the PIN-TIA. At the transmitter side, the -3dB
modulation bandwidth was measured to be 11.86GHz and an OC-192 eye diagram with 19% mask margin was obtained.
At the receiver side, the sensitivity was -13.1dBm at the bit error rate of 10-9 and the eye mask margin of OC-192 was
more than 30%.
Electron-determined nonuniform carrier distribution inside multiple quantum wells (MQW) is experimentally discovered. Two groups of mirror-imaged nonidentical quantum well InGaAsP/InP lasers diodes are designed, fabricated, and measured. Measured characteristics of both groups show that electron, instead of hole, is the dominant carrier affecting carrier distribution. Carrier transport effects including carrier diffusion/drift and capture/emission processes inside MQW are described to explain the nonuniform carrier distribution. The reason for the electron dominated carrier distribution is because electron takes less time to be capture into QW 2D states than hole does. The sequence of the nonidentical QWS is also shown to have significant influence on device characteristics.
Extremely broadband emission is obtained from superluminescent diodes/semiconductor laser amplifiers with nonidentical quantum wells made of InGaAsP/InP materials. Two opposite sequences of nonidentical multiple quantum wells (MQWs), consisting of three In0.67Ga0.33As0.72P0.28 quantum wells and two In0.53Ga0.47As QWs, are designed, fabricated, and measured. Nonuniform carrier distribution inside MQWs is further verified experimentally.
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